Very cold and unstable SW blast, Eastern SI 25th Sept

Razor · Unread post by **Razor** » Wed 25/09/2019 10:43

Its clouding over from the NW, could be a negative?

Cyclone Tracy · Unread post by **Cyclone Tracy** » Wed 25/09/2019 10:50

snowchaser01 wrote: ↑Wed 25/09/2019 08:57
Cyclone Tracy wrote: ↑Wed 25/09/2019 08:44 8am water vapour sat pic showing a significant dual airflow upper polar injection with moisture pluming around the -38c @500 hPa cold pool just off the SI.
CT, interested to know if you believe this is directly related to the SSW, and what are your thoughts on this afternoon in Canterbury? Appreciated as always.

It's the SSW affect is going into 2nd gear. There are 8 separate streamers now coming out of the tropospheric polar vortex in our part of the world.

An aggressive negative SAM (AAO) phase which the GEFS ensemble is starting to show in Oct, will be characterised by an outbreak of cut off lows in the mid latitudes, this would include synoptic scale cyclonic Tasman and South Pacific gyre development.

As for Canterbury today and tonight, NZ Storm, Tony and others have given some good feedback. I think it deserves thread

snowchaser01 · Unread post by **snowchaser01** » Wed 25/09/2019 10:53

Think this deserves a new thread, plenty of discussion around it.

Chris W · Unread post by **Chris W** » Wed 25/09/2019 10:56

Of all the days to be in Kaikoura!

Chris W · Unread post by **Chris W** » Wed 25/09/2019 10:56

Awhituobs · Unread post by **Awhituobs** » Wed 25/09/2019 10:56

Met Service on twitter said this outbreak is more to do with a stormy SAM than the SSW

Chris W · Unread post by **Chris W** » Wed 25/09/2019 10:58

The SAM is surely influenced by the SSW, MS just don't want to hype it IMO.

Chris W · Unread post by **Chris W** » Wed 25/09/2019 11:09

Strong convection after surface heating with -5C 850mb, -11/12C 700mb and -35C 500mb temperatures (GFS)
Snow showers to sea level (quoting Metservice thunderstorm outlook)
Severe thunderstorm watch and thunder for much of the North Otago and South-North Canterbury coast, thunder for Southland and the west coast
Large hail accumulations
Strong wind
Bring back Buck

Or will it fizz?

Very interesting afternoon and evening ahead.

TonyT · Unread post by **TonyT** » Wed 25/09/2019 11:10

Awhituobs wrote: ↑Wed 25/09/2019 10:56 Met Service on twitter said this outbreak is more to do with a stormy SAM than the SSW

They have been behind the 8 ball on this SSW event all along. What they don't seem to get is that the AAO does not drive our weather. Its a measure of the interaction of processes which do. And the SSW is giving the AAO a fair old nudge.

snowchaser01 · Unread post by **snowchaser01** » Wed 25/09/2019 11:27

Multiple cm's to sea level.. not out of the question if a big beefy shower or two moves through IMO

melja · Unread post by **melja** » Wed 25/09/2019 11:40

Classic NW day here in Chch now, wind from NW too.

Sent from my Lenovo K50a40 using Tapatalk

03Stormchaser · Unread post by **03Stormchaser** » Wed 25/09/2019 11:48

melja wrote: ↑Wed 25/09/2019 11:40 Classic NW day here in Chch now, wind from NW too.

Sent from my Lenovo K50a40 using Tapatalk

NE - NNE in the City, SE at New Brighton and NW up Sugarloaf, all very light winds.

Razor · Unread post by **Razor** » Wed 25/09/2019 12:26

Warm and sunny now in town and looking promising to the SW

hozza95 · Unread post by **hozza95** » Wed 25/09/2019 12:43

It's been dry here most of the morning but now we've had a few heavy hail showers.

Chris Raine · Unread post by **Chris Raine** » Wed 25/09/2019 12:51

Temp fell from 9.7C to 4.8C an hour ago with light rain and a SW change

03Stormchaser · Unread post by **03Stormchaser** » Wed 25/09/2019 12:59

First wee cell over Birdlings Flat, went from noting on radar to something in 15min!

snowchaser01 · Unread post by **snowchaser01** » Wed 25/09/2019 13:09

Certainly very unstable air around.. after 3-4pm is when it gets really interesting though i think.

Razor · Unread post by **Razor** » Wed 25/09/2019 13:10

From the office...

Powermad · Unread post by **Powermad** » Wed 25/09/2019 13:14

03Stormchaser wrote: ↑Wed 25/09/2019 12:59 First wee cell over Birdlings Flat, went from noting on radar to something in 15min!

I reckon that was Lake Ellesmere that caused that.

snowchaser01 · Unread post by **snowchaser01** » Wed 25/09/2019 13:16

Powermad wrote: ↑Wed 25/09/2019 13:14
03Stormchaser wrote: ↑Wed 25/09/2019 12:59 First wee cell over Birdlings Flat, went from noting on radar to something in 15min!
I reckon that was Lake Ellesmere that caused that.

Same thing just happened as a VERY SMALL cell passed over Rakaia river... as it passed over it intensified rapidly....

03Stormchaser · Unread post by **03Stormchaser** » Wed 25/09/2019 13:21

Yeah that Rakaia cell has exploded, on track for the city...

Razor · Unread post by **Razor** » Wed 25/09/2019 13:23

Snowing at Arthurs Pass, Transit NZ advise chains essential

snowchaser01 · Unread post by **snowchaser01** » Wed 25/09/2019 13:26

03Stormchaser wrote: ↑Wed 25/09/2019 13:21 Yeah that Rakaia cell has exploded, on track for the city...

Has gone nuts in the last 15 mins... and continues to do so. Gust front?

mikestormchaser · Unread post by **mikestormchaser** » Wed 25/09/2019 13:37

That cell when it hits lake ellesmere may intensify.. either skirt out towards birdlings and past BP or come for the city.

hozza95 · Unread post by **hozza95** » Wed 25/09/2019 14:15

Temp dropping quickly here now. Down to 3.8 and a real chill in the air even though it’s just overcast and not much wind.

NZ Weather Forum

Very cold and unstable SW blast, Eastern SI 25th Sept

Re: General September Weather

Re: General September Weather

Very cold and unstable SW blast, Eastern SI 25th Sept

Re: General September Weather

Re: General September Weather

Re: General September Weather

Re: General September Weather

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: General September Weather

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept

Re: Very cold and unstable SW blast, Eastern SI 25th Sept